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Abstract:

A method for perceptual enhancement of a received remote talker's voice,
in the presence of local ambient noise, in an electronic voice
communication system is provided. The method includes generating a pair
of binaural voice signals from the remote talker's voice and manipulating
the characteristics of the resulting pair of binaural signals. The two
ears of the local listener are stimulated binaurally with the pair of
binaural voice signals. The stimulating is performed adaptively as the
ambient noise in the local listener's environment changes, thereby
creating a perception of remote talker reacting actively to the local
ambient noise, in a psycho-acoustically pleasing manner to the local
listener.

Claims:

1. A method for perceptual enhancement of a remote talker's voice, in the
presence of local ambient noise, in an electronic voice communication
system, comprising: generating a pair of binaural voice signals from the
remote talker's voice; manipulating characteristics of the pair of
binaural voice signals; and stimulating ears of a listener binaurally
with the pair of binaural voice signals, the stimulating performed
adaptively as the ambient noise in a listener's environment changes,
thereby creating a perception of a remote talker reacting actively to the
ambient noise in the listener's environment.

2. The method of claim 1, wherein the perception functions to make the
remote talker's voice to virtually emanate from a direction different
from that of the local ambient noise source.

3. The method of claim 2, wherein the manipulating introduces a time
delay between the signals of the pair of binaural voice signals.

4. The method of claim 2, wherein the manipulating introduces a
difference in attenuation between the signals of the pair of binaural
signals.

5. The method of claim 1, wherein the perception functions to make the
remote talker's voice emanate from within a head of the listener.

6. The method of claim 5, wherein the manipulating inverts a phase of the
pair of binaural signals.

7. The method of claim 1, wherein the ambient noise is diffused and
wherein the perception functions to make the ambient noise arrive from a
direction different from that of a direction of the remote talker's
voice.

8. The method of claim 7 wherein the manipulating further comprises:
sensing the local ambient noise; and stimulating one of the ears with a
signal having more of the local ambient noise that a signal to another
one of the ears.

9. The method of claim 1, wherein the perception functions to make the
remote talker to move around.

10. The method of claim 1, wherein the perception functions to make the
remote talker shout.

12. The method of claim 1, wherein the stimulating is achieved through a
surround sound system.

13. The method of claim 1, wherein the stimulating is achieved using a
binaural headset.

14. The method of claim 1, wherein the stimulating is achieved using a
stereo sound system.

Description:

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Patent Application No.
61/486,088, filed on May 13, 2011, and entitled "PSYCHO-ACOUSTIC NOISE
SUPPRESSION," which is incorporated herein by reference.

BACKGROUND

[0002] Recent developments in the art of manufacturing has brought
significant reduction in cost and form factor of mobile consumer
devices--tablet, blue tooth headset, net book, net TV etc. As a result,
there is an explosive growth in consumption of these consumer devices.
Besides communication applications such as voice and video telephony,
voice driven machine applications are becoming increasing popular as
well. Voice based machine applications include voice driven automated
attendants, command recognition, speech recognition, voice based search
engine, networked games and such. Video conferencing and other display
oriented applications require the user to watch the screen from a
hand-held distance. In the hand-held mode, the signal to noise ratio of
the desired voice signal at the microphone is severely degraded, both due
to the exposure to ambient noise and the exposure to loud acoustic echo
feedback from the loudspeakers in close proximity. This is further
exacerbated by the fact that voice driven applications and improved voice
communications require wide band voice.

[0003] Binaural headsets, both wired and wireless have been increasing
along with the explosive growth of mobile consumer devices. However, the
noise environments in which the headsets are used are becoming ever more
challenging, especially in the presence of ambient noise in the
environment of the listener.

[0004] It is within this context that the embodiments arise.

SUMMARY

[0005] The embodiments provide take advantage of the observation that the
human brain has naturally evolved to perform noise suppression by taking
advantage of several cues in the environment. On a lighter note, it is
this ability which makes a husband completely miss hearing his wife,
while he may be busy watching a TV show.

[0006] In the present embodiments, an arbitrary number of microphones are
bifurcated into two groups. The microphones in each group are summed
together to form two microphone arrays. Due to the computing ease of the
processing operation, i.e., summing, these arrays by themselves provide
very little improvement of signal to noise ratio in the desired look
direction. However, the microphones are arranged such that the
characteristics of the ambient noise from other directions orthogonal to
the look direction, is substantially different between the outputs of the
two microphone arrays. The embodiments employ a source separation
adaptive filtering process between these two outputs to generate the
desired signal with substantially improved signal to noise ratio. The
separation process also provides ambient noise with significantly reduced
voice. There are applications where the ambient noise is of use. The
outputs of a multiplicity of microphones is reduced or encoded into two
signals, i.e., the virtual microphones. With the reduced bandwidth and
fixed signal dimension, it is easier to perform the processing through
existing hardware and software systems, such that the processing of
interest may be performed either on the end hosts or the network cloud.

[0007] The above summary does not include all aspects of the present
invention. The invention includes all systems and methods disclosed in
the Detailed Description below and particularly pointed out in the
claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The embodiments of the invention are illustrated by way of examples
and not be interpreted by way of limitation in the accompanying drawings.

[0009] FIG. 1 illustrates noise and voice signals originating from a same
direction.

[0011] FIG. 3 illustrates a simplified schematic diagram illustrating a
technique to excite the ears of a listener with a pair of stereo or
binaural signals to create psycho acoustic effects in accordance with one
embodiment of the invention.

DETAILED DESCRIPTION

[0012] While several details are set forth, it is understood that some
embodiments of the invention may be practiced without these details. In
some instances, well-known circuits and techniques have not been shown in
detail so as not to obscure the understanding of this description.

[0013] Active Noise Control has been utilized to generate anti-noise in
the ears of the listener. However, active noise control requires a
fully-covered headset, making it expensive and inconvenient
Implementations which use smaller headsets have not fared well in the
quality of enhancement.

[0014] Adaptive Volume Control, where the volume of the remote talker's
voice is increased in the listener's ears based on the loudness of
ambient noise has also been utilized to address this problem. However,
this method has a limited useful range in which the volume can be varied
without hurting the listener's ears.

[0015] The following psycho-acoustic observations of interest provide a
basis for the embodiments described below: [0016] a. Human hearing is
more sensitized to directional sound as compared to diffused sound coming
from all over. [0017] b. Human hearing can differentiate two sources of
sound better if it comes from two different directions as shown in FIG.
2, rather than coming from the same direction as shown in FIG. 1. [0018]
c. Human hearing is more sensitized to a whisper in the ear rather than
an equally loud sound from a distance. [0019] d. Human hearing is
sensitized to a shout out from a distance. Shouting makes the voice
different--it has the so called Lombard's effect. [0020] e. Human hearing
is sensitized to a moving sound source as compared to a diffused source
of sound

[0021] In the embodiments described above, a plurality of microphones is
bifurcated into two groups. As shown in FIG. 3, methods to excite the two
ears of the listener with a pair of stereo, or binaural signals, creating
the desired psycho-acoustic effects is provided. The effects processing
is made adaptive with the ambient noise characteristics such as direction
of arrival of the noise and its loudness. The effects include the
following: [0022] Playing the remote talker's voice in the two ears
with different delays to create a perception of desired directionality.
[0023] Playing the remote talker's voice in the two ears with different
attenuation to further support the perception of desired directionality.
[0024] Making the diffused ambient noise seem directional by mixing some
of the noise sensed from the environment into one of the ears. It should
be appreciated that this makes the listener hear the noise more in one of
the ears. [0025] Playing the remote talker's voice in the two ears with a
phase inversion to create the perception of the voice emanating from
within the head of the listener. [0026] Introducing Lombard's effect into
the remote talker's voice through signal processing, to create a
perception that the remote talker is shouting to keep up with the ambient
noise around the listener.

[0027] The received remote talker's voice is mono. We make two copies for
the left and right channels to be processed and fed to the two speakers
of the stereo headset as shown in FIG. 3. Using the local microphones in
the device, we sense the ambient noise. There are several ways to sense
ambient noise, some described by the authors in other patents. From this
sensor, we can determine the intensity and direction of the ambient
noise. The two copies of the remote talker's signals are manipulated
based on the sensed ambient noise. In one example of the manipulation, we
delay the two copies to make it seem to arrive from a direction different
from that of the ambient noise. In the event the ambient noise does not
have a preferred direction, such as the vase of diffused noise, we
artificially make it seem as though it is directional. This is achieved
by taking some of the observed noise and adding it towards one of the
ears, so the listener is led to believe that the noise is arriving from
that direction. In addition, we also propose introducing Lombard's
effect, in effect making it sound as though the remote talker's is
shouting in response to the ambient noise in the local listener's
environment. It should be appreciated that while FIG. 3 illustrates a
binaural headset, the same effect can be realized using stereo or
surround speaker systems as well.

[0028] With the above embodiments in mind, it should be understood that
the embodiments might employ various computer-implemented operations
involving data stored in computer systems. These operations are those
requiring physical manipulation of physical quantities. Usually, though
not necessarily, these quantities take the form of electrical or magnetic
signals capable of being stored, transferred, combined, compared, and
otherwise manipulated. Further, the manipulations performed are often
referred to in terms, such as producing, identifying, determining, or
comparing. Any of the operations described herein that form part of the
invention are useful machine operations. The embodiments also relates to
a device or an apparatus for performing these operations. The apparatus
can be specially constructed for the required purpose, or the apparatus
can be a general-purpose computer selectively activated or configured by
a computer program stored in the computer. In particular, various
general-purpose machines can be used with computer programs written in
accordance with the teachings herein, or it may be more convenient to
construct a more specialized apparatus to perform the required operations

[0029] The invention can also be embodied as computer readable code on a
computer readable medium. The computer readable medium is any data
storage device that can store data, which can be thereafter read by a
computer system. Examples of the computer readable medium include hard
drives, network attached storage (NAS), read-only memory, random-access
memory, CD-ROMs, CD-Rs, CD-RWs, magnetic tapes, and other optical and
non-optical data storage devices. The computer readable medium can also
be distributed over a network coupled computer system so that the
computer readable code is stored and executed in a distributed fashion.
Embodiments of the present invention may be practiced with various
computer system configurations including hand-held devices,
microprocessor systems, microprocessor-based or programmable consumer
electronics, minicomputers, mainframe computers and the like. The
invention can also be practiced in distributed computing environments
where tasks are performed by remote processing devices that are linked
through a wire-based or wireless network.

[0030] Although the method operations were described in a specific order,
it should be understood that other operations may be performed in between
described operations, described operations may be adjusted so that they
occur at slightly different times or the described operations may be
distributed in a system which allows the occurrence of the processing
operations at various intervals associated with the processing.

[0031] Although the foregoing invention has been described in some detail
for purposes of clarity of understanding, it will be apparent that
certain changes and modifications can be practiced within the scope of
the appended claims. Accordingly, the present embodiments are to be
considered as illustrative and not restrictive, and the invention is not
to be limited to the details given herein, but may be modified within the
scope and equivalents of the appended claims.